It is usually required to perforate a back cover of a mobile phone and provide an outward protrusion on the back cover by punching. A camera module is arranged corresponding to the protrusion, and a camera head stretches into the protrusion, such that the camera module is accommodated and the overall thickness of the mobile phone is relatively small. However, because of the need to provide the protrusion on the back cover by punching, the structure of the back cover is complicated, and the manufacturing yield of the back cover is low.